Can I get all validation errors in spring boot web application?

Question

I have a pojo like below (please assume a controller and rest of the code. Application is in Spring boot):

@Getter  @Setter
@AllArgsConstructor  @NoArgsConstructor
public class User  {
    @NotBlank(message = "userName is blank")
    private String userName;

    @NotBlank(message = "secretKey is blank")
    private String secretKey;
}

and defined a ExceptionHandler class annotated with @ControllerAdvice and defined a method as bellow:

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(value = {MethodArgumentNotValidException.class})
    protected ResponseEntity<ErrorResponse> handleMethodArgNotValidException(MethodArgumentNotValidException ex,Locale locale) {
        // code to handle exception.
    }

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(value = {WebExchangeBindException.class})
    protected ResponseEntity<ErrorResponse> handleException(WebExchangeBindException ex, Locale locale) {
        // code to handle exception.
    }

But in this case even if both fields have validation errors client is getting only one.

I want to ask that is there any way I can list out all the validation errors in the response of this endpoint?

curl --location --request POST 'localhost/api/login' \
--header 'Content-Type: application/json' \
--data-raw '{
    "userName": null,
    "secretKey": null
}'

Answer 1

You can get the BindingResult from MethodArgumentNotValidException and then compose a message based on all rejected fields, for example:

@ControllerAdvice
public class GlobalExceptionHandler {

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(value = {MethodArgumentNotValidException.class})
    protected ResponseEntity<ErrorResponse> handleMethodArgNotValidException(MethodArgumentNotValidException ex, Locale locale) {

        String errorMessage = ex.getBindingResult()
                .getFieldErrors()
                .stream()
                .map(fieldError -> fieldError.getField() + ": " + fieldError.getDefaultMessage())
                .collect(Collectors.joining("; "));

        // put errorMessage into ErrorResponse
        // return ResponseEntity<ErrorResponse>
    }
}

Example of possible output with message:

{
    "timestamp": "2022-01-28T17:18:53.1738558+03:00",
    "status": 400,
    "error": "BadRequest",
    "errorMessage": "userName: userName is blank; secretKey: secretKey is blank"
}